1. Field of the Invention
The present invention relates to a boat propulsion system and a boat including the same, and also relates to a boat control device and a boat control method.
2. Description of the Related Art
Conventionally, various boat propulsion systems such as an inboard motor, an outboard motor, a so called stern drive, etc. are known. As disclosed in JP-A-Hei 9-104396, for example, an output of the boat propulsion system is generally controlled based on a rotational speed of an engine or a propeller. In particular, the output of the boat propulsion system is generally controlled such that the rotational speed of the engine or the propeller follows the rotational speed corresponding to an operating amount of a control lever controlled by an operator.
There are some cases in which, even if the rotational speed of the engine or the propeller is the same as the rotational speed corresponding to an operating amount of a control lever controlled by an operator, an actual thrust obtained by the boat propulsion system differs under different sea conditions. Accordingly, when the rotational speed of the engine or the propeller is controlled to follow the rotational speed corresponding to the operating amount of the control lever, the obtained thrust may differ for the same operating amount of the control lever.